This invention relates to improvements in scabbler bits.
Scabbler bits comprise a plurality of tungsten carbide tips or slugs fitted in the base of a carrier which in turn is fixed to a reciprocating piston of a scabbling machine. Scabbler bits are known in which the carrier is the form of a cylindrical member which is closed at one end to form a base, on the outer surface of which there are fitted the tungsten carbide tips. Such scabbler bits fit over a male piston and a typical example of a prior art scabbler bit is illustrated in FIG. 1a. The bit comprises a cylindrical female carrier 1 having a plurality of tips 2 and fixable to a male piston (not shown) by means of a fixing pin passing through holes 3, 4 in the carrier 1. Such a design of bit involves considerable machining and is not readily fitted to or removed from the piston when it is desired to change the bit.
Further, in order to present wide coverage whilst scabbling, hitherto proposed scabbler bits have employed various arrangements of, for example, five, seven and nine tips as illustrated in FIG. 1b to 1d.
Each of these arrangements suffers from a number of disadvantages one of which is that the rotating scabbler bit presents a different cutting diameter in the direction of movement of the scabbler. This results in the formation of non-uniform channels since the cutting width W.sub.1 in one direction is less than the cutting width W.sub.2 in another direction in each of the configurations illustrated. A second disadvantage is that a central tip is required to ensure that there does not result an uncut portion along the centre of the channel.
It is an object of the present invention to obviate or mitigate these disadvantages.